Many times it is desirable to have variable length cords without cutting the cord to a shorter length or obtaining various lengths of separate cords. This is particular true when the cord is an elastic stretchable cord such as a bungee cord since the usable effective length can vary depending on the of tensioning force applied.
One very simple solution would be to tie one or more a knots in the cord along its length. This has the disadvantage of having to untie these knots afterwards which may not be an easy affair if the cord had been subjected to considerable tension with the knots tightened on it. Another disadvantage of using knots is that the cord is acting against itself when tensioned thereby subjecting the cord to a certain amount of destructive force.
Another commonly used method to shortening the effective length of a cord is to use a cleat upon which the cord is wound. This cleat is usually fixed to a stationary object, such as a pole or a dock's upright pier, and the cord is wound around the cleat a number of times until the desired effective length is obtained.
A method to adjust the effective rigidity of an elastomer cord involves constructing a cord of an inner elastomer rope with a reinforcement wound helically around the rope that is considerably less elongateable than the elastomeric material and using an outer cover layer of elastomeric material. Under tension changes in the diameters of the elastometer and the reinforcement material are different to permit the desired progressively of the force necessary to produce a definite additional further elongation.
With some bungee or bungee cord systems, a control system using pulleys and cord length adjustors using karabiners have been used. And in a more complicated system a variable level platform suspended from the gantry of a cargo container has been employed to shorten the spreader lift lines.
The present invention differs from the foregoing cord shortening devices by providing for a one piece cord shortening device which provides for both the shortening of the cord and its retention in the shortened state all as more fully explained hereafter.